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arXiv 1209.6005math.NT
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具有同构交换伽罗瓦群的虚二次域

Imaginary quadratic fields with isomorphic abelian Galois groups

Athanasios Angelakis, Peter Stevenhagen

摘要:

在1976年,Onabe发现,与Neukirch-Uchida的结果相反,在同一时间被证明,数域$K$不完全由它的绝对阿贝尔伽罗瓦群$A_K$来刻画。具有同构$A_K$的非同构$K$的第一个例子是在久保田根据Ulm不变量的无限族对idele类特征标群进行分类的基础上获得的,并且没有得到$A_K$的描述。本文给出了虚二次$K$的投射有限群$A_K$的一个直接“计算”,并利用它得到了许多不同的具有相同的最小绝对交换伽罗瓦群的$K$.

英文摘要:

In 1976, Onabe discovered that, in contrast to the Neukirch-Uchida results that were proved around the same time, a number field $K$ is not completely characterized by its absolute abelian Galois group $A_K$. The first examples of non-isomorphic $K$ having isomorphic $A_K$ were obtained on the basis of a classification by Kubota of idele class character groups in terms of their infinite families of Ulm invariants, and did not yield a description of $A_K$. In this paper, we provide a direct `computation' of the profinite group $A_K$ for imaginary quadratic $K$, and use it to obtain many different $K$ that all have the same minimal absolute abelian Galois group.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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